Serotonin 5-HT2C receptor is one of the receptors of the biological transmitter serotonin, which is distributed mainly in the central nervous system and controls many physiological functions in vivo. A representative example is the control of appetite. It has been demonstrated in a study using rodents that stimulation of the central serotonin 5-HT2C receptor decreases eating behavior, resulting in decreased body weight. It has also been reported that, in human as well, administration of a serotonin 5-HT2C receptor activator suppresses appetite and decreases body weight (see non-patent document 1). In addition, it has been demonstrated in a rat test using a serotonin 5-HT2C receptor activator that stimulation of the central serotonin 5-HT2C receptor suppresses depression-related behaviors (see non-patent document 2), and has also been reported to be effective for many central nervous diseases such as anxiety etc. (see non-patent document 3).
The serotonin 5-HT2C receptor is also highly expressed in the parasympathetic nucleus and motor neurons in the sacral spinal cord, and is considered to control the peripheral nervous functions (see non-patent document 4). It has been reported that when a serotonin 5-HT2C receptor activator is administered to rats, penile erection is induced (see non-patent document 5), and urethral resistance is increased (see patent document 1); all these actions are attributed to stimulation of the serotonin 5-HT2C receptor in the sacral spinal cord.
For serotonin 5-HT2C receptor activators, many clinical applications are likely, with particular expectations for anti-obesity drugs, anti-depressants, anti-anxiety drugs, therapeutic drugs for male erectile dysfunction, and therapeutic drugs for stress urinary incontinence and the like.
As serotonin 5-HT2C receptor compounds, the following compounds have been reported.
Thiophenyl or pyrrolylazepine compound has been disclosed as a therapeutic drug for addiction, anxiety, depression, obesity and the like (see Patent Document 2), and fibromyalgia therapeutic effect of a serotonin 5-HT2C receptor agonist compound has been reported (see Patent Document 3). It has also been reported that compounds having no serotonin 5-HT2 receptor agonist action are found out as psychotropic agent for central nerve (see Non-Patent Document 6). There is a demand for the development of compounds having useful efficacy and the like, however, none of the documents have been reported the compound of the present invention.    Non-Patent Document 1: Expert Opinion on Investigational Drugs, 2006, vol. 15, page 257    Non-Patent Document 2: J. Pharmacol. Exp. Ther., 1998, vol. 286, page 913    Non-Patent Document 3: Pharmacology Biochemistry Behavior, 2002, vol. 71, page 533    Non-Patent Document 4: Neuroscience, 1999, vol. 92, page 1523    Non-Patent Document 5: Eur. J. Pharmacol., 2004, vol. 483, page 37    Non-Patent Document 6: Bioorg. Med. Chem. Lett., 1998, vol. 8, page 983    Patent Document 1: WO 2004/096196 pamphlet    Patent Document 2: WO 2007/084622 pamphlet    Patent Document 3: WO 2011/071136 pamphlet